The present invention relates to electronic monitoring systems, and particularly to such systems useful as "babysitters" for monitoring a particular space from a remote location.
A number of monitoring systems have been devised for use as electronic babysitters. In general, the known systems include radio transmitters which transmit the sounds from the monitored area to a radio receiver carried by the parent. However, such known systems are of limited range because of the need to regulate radio transmissions in view of the crowded condition of the air-waves.
An object of the present invention is to provide an electronic monitoring system, particularly useful as a babysitter, which enables almost any area to be conveniently monitored from a virtually unlimited range.
According to the present invention, there is provided an electronic monitoring system comprising monitoring means connectable to the telephone line at the location to be monitored; and a portable sound-producing unit for transmitting first and second codes to the monitoring means via a remote telephone and the telephone line. The monitoring means includes: a microphone for picking up local sounds at the location to be monitored; a sound level comparator comparing the sounds picked up by the microphone with a predetermined threshold value; means for manually presetting and storing the number of a selected remote telephone; a code detector for detecting the code transmitted by the portable sound-producing unit to the monitoring means via the remote telephone and the telephone line; and automatic dialing means for automatically dialing the selected remote telephone number. The system further includes alarm indicating means indicating an alarm condition when the sound picked up by the microphone exceeds the predetermined threshold value for a predetermined time; and means effective: (a) upon detecting the first code from the portable sound-producing unit to enable the listener at the remote telephone to hear via the telephone line the sounds picked up by the microphone; and (b) upon detecting the second code from the portable sound-producing unit, to automatically dial the selected remote telephone number whenever the alarm condition is indicated by the alarm indicating means.
Further features and advantages of the invention will be apparent from the description below.